SoapFault exception: [soapenv:Server] Exception occurred whi

When trying to use WriteBackWebService to update attendance records a I seem to have an issue with the method, every time I call it I'm getting an Exception of

"SoapFault exception: [soapenv:Server] Exception occurred while trying to invoke service method ******"

Have tried this with multiple methods.

My question is, is this down to the connection to the server being an issue or something more to do with the data or method?